> I have used the MC34063 in another design.  For the two LED driver design=
s
> next up to do, one must be highest efficiency and run from 48V - it is 11
> channels driving a total of nearly 200W of LEDs, so MC34063 can't do it (=
40V
> max input).  The other is 12-24V and efficiency is not top priority so th=
e
> MC34063 is a possibility, although the user could put 1 LED or several in=
 series
> on any channel, so the design would have to work with all combinations of
> 12V or 24V in, and a single 3V LED to (Vin minus say 3 volt headroom) str=
ing of
> LEDs.

Running 200W of LEDs is going to require some power electronics or multiple=
 converters.

My suggestion is multiple converters each driving a separate string of LEDs=
 so that if one fails you have some redundancy.

To run from 48V I would suggest looking at the chips designed for mains ope=
ration light bulbs, where a converter will run a string of LEDs for around =
5-10W of light per chip. I don't know what minimum voltage the off-line chi=
ps will run at, but would start there.

An alternative source would be to scour Linear Technology and TI for chips =
designed to run on the new standard 48V automotive systems.
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